mxfmux : Mxfmux is not functional with splitmuxsink

Submitted by Baby octopus

Description

There are two issues

Pad templates of mxfmux is not generic like that of mp4. Splitmuxsink does't have support for such pad templates(ex: mpeg_audio_sink_%u). Its good to have generic pad template such as audio_%d, video_%d etc

With workaround for above issue(hardcoding in splitmuxsink), I tried to run a pipeline to fragment filed and mux them into MXF. Issue happens during the creation of second fragment. EOS isn't handled properly I guess which is leading to crash.